1. Field of the Invention
The invention relates to electronic assemblies adapted to operate in relatively harsh service environments.
2. Background Art
Modern electronic assemblies must often operate in relatively harsh environments. For example, in some automotive applications, electronic assemblies must be able to withstand severe vibration, drastic temperature fluctuations (e.g., between about -40.degree. C. and about 125.degree. C.), corrosive and/or particle-laden exhaust fumes, high atmospheric moisture, and so forth. In response, the prior art teaches providing mechanical protection for an electronic assembly by placing the electronic assembly within a protective housing. The prior art also teaches providing an electronic assembly with a measure of resistance to moisture and/or chemical attack by potting the entire assembly, or portions thereof, in a relatively moisture-impervious potting material, such as an epoxy or silicone material.
In accordance with another prior art approach, as disclosed in U.S. Pat. No. 5,317,478, a hermetically-sealed electronics package includes an electronic element located on a multilayer flexprint substrate. A cover, which may itself form the top layer of the multilayer flexprint or a separate flexprint, is supported above the electronic element by a frame structure, whereupon a periphery of the cover is sealingly attached to the substrate. The frame structure provides support for the flexprint cover to prevent deformation of the cover and resulting damage to the underlying circuit. The electronics package is thereafter itself attached to a suitable mounting structure within the vehicle.
However, these and other previously-known approaches often suffer from one or more drawbacks. For example, even when generally well-sealed against water penetration, known protective housings typically fail to protect the assembly's electronic components against long-term moisture penetration, e.g., due to the diffusion of moisture through a given potting material, whereupon the penetrated moisture will likely detrimentally affect the performance, functionality and/or service life of the assembly's electronic components. And, in the event that certain contaminants are either trapped within the potted assembly or, alternatively, form a portion of the service environment within which the assembly is operated, the moisture and contaminants can often combine within the assembly to form a corrosive solution, thereby further deteriorating the performance, functionality and service life of the assembly's components. Moreover, the requirement of separate supporting structures upon which to mount each sealed prior art electronics package will be seen to substantially increase manufacturing and assembly complexity and cost.